1. Field of the Invention
The present invention is directed to selected oxyalkylated 2,6-dialkylphenol compounds and their use as stabilizers of organic materials against oxidative degradation. In particular, the present invention is directed to selected bis(4-oxyalkylated-2,6-dialkylphenol) adducts of ethylenediaminetetraacetic acid as novel compositions of matter and their use as stabilizers of organic material against oxidative degradation.
2. Description of the Prior Art
Many organic materials suffer oxidative degradation. This problem is particularly acute in plastics and other synthetic polymers where degradation may readily occur under the high temperatures normally associated with their processing. Degradation also results in such polymers after long-term aging under ambient conditions. In order to stabilize or protect these organic materials from oxidative degradation, certain antioxidant chemical additives have been incorporated into these materials either before or during processing.
It is also known that certain metals (e.g. copper), when in contact with or as impurities of the organic materials, may catalyze this oxidative degradation. Thus, metal deactivating agents are incorporated in such organic materials.
Combinations of antioxidant additives are often used to improve oxidative stability. Certain combinations of antioxidants provide a synergistic amount of antioxidant activity. See U.S. Pat. No. 3,535,277, which issued to Miller et al on Oct. 20, 1970. Such combinations may be made by reacting together two or more antioxidant additives to form a single compound having two or more antioxidant moieties. This approach is taught in U.S. Pat. Nos. 4,413,077, which issued to Valdiserri et al on Nov. 1, 1983, and 4,414,408, which issued to Cottman on Nov. 8, 1983. Separately, antioxidant moieties have been chemically bonded to known metal deactivators. See U.S. Pat. No. 4,012,360 which issued to Schwarzenbach et al on Mar. 15, 1977.
2,6-Dialkyl substituted phenols are well known in the art as antioxidant moeities. Furthermore, the reaction of such moieties with other antioxidant moieties to provide multifunctional antioxidant molecules is known. See U.S. Pat. Nos. 3,285,855, which issued to Dexter et al on Nov. 15, 1966; 3,526,668, which issued to Starnes et al on Sept. 1, 1970; and 3,975,360, which issued to Kline on Aug. 17, 1976.
These 2,6-dialkyl substituted or hindered phenolic stabilizers, while being reasonably effective stabilizers for organic materials, may have operating problems associated with them. Specifically, they are known to cause discoloration or staining to some organic materials they intend to stabilize. They also may be too readily volatilized, and, therefore, will escape from the material they are stabilizing. This will result in a lowered antioxidant level and will shorten the service life of that material. These hindered phenolics are also known to be ineffective in the presence of transition metals (e.g., copper) as in the case of plastic covering for wiring or where metal impurities occur in the organic material.
In view of these facts, there is a need for new antioxidants and metal deactivators which have improved effectiveness against oxidative degradation over a wide variety of applications.
It is therefore an object of this invention to provide a new class of relatively nondiscoloring and nonvolatile hindered phenolic stabilizers for oxidizable organic materials.
It is also an object of this invention to provide a new class of hindered phenolic stabilizers which are effective in the presence of transition metals.
These and other objects of the invention will be apparent from the following detailed description of the invention.